Description: Reverse closure for the class of universal property in opposite categories. (Contributed by Zhi Wang, 4-Nov-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | oppcuprcl2.x | |- ( ph -> X ( <. F , G >. ( O UP P ) W ) M ) |
|
| oppcuprcl4.o | |- O = ( oppCat ` D ) |
||
| oppcuprcl4.b | |- B = ( Base ` D ) |
||
| Assertion | oppcuprcl4 | |- ( ph -> X e. B ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | oppcuprcl2.x | |- ( ph -> X ( <. F , G >. ( O UP P ) W ) M ) |
|
| 2 | oppcuprcl4.o | |- O = ( oppCat ` D ) |
|
| 3 | oppcuprcl4.b | |- B = ( Base ` D ) |
|
| 4 | 2 3 | oppcbas | |- B = ( Base ` O ) |
| 5 | 1 4 | uprcl4 | |- ( ph -> X e. B ) |